The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Recently, a typical internal combustion engine vehicle using fossil fuel as fuel has problems of environmental pollution due to exhaust gas, global warming due to carbon dioxide, a cause of a respiratory disease due to ozone generation, etc. Further, fossil fuel present on the earth is restrictive and therefore may be exhausted in the near future.
Therefore, to solve the above problems, an electric vehicle driven by an electric motor, a hybrid electric vehicle driven by an engine and the electric motor, a fuel cell vehicle driving an electric motor with power generated from a fuel cell, etc., have been developed as eco-friendly vehicles.
A power conversion apparatus is equipped in the eco-friendly vehicle, in which the power conversion apparatus is generally configured to include a high voltage battery and an auxiliary battery and a low voltage DC/DC converter (LDC) which converts a voltage of the high voltage battery into a voltage for charging the auxiliary battery.
Therefore, the eco-friendly vehicles such as a hybrid vehicle and an electric vehicle use both of the high voltage battery and the auxiliary battery, in which the high voltage battery supplies special power to a driving system, an air conditioner, a heater, etc., of a vehicle and the auxiliary battery supplies power to low voltage vehicle loads like a system of the typical vehicle. Further, when the power of the auxiliary battery is insufficient due to the continuous supply of power from the auxiliary battery to the vehicle loads, the auxiliary battery is charged by the LDC.
Therefore, various technologies for the system and method for charging an auxiliary battery using an LDC have been developed. A method for charging an auxiliary battery is provided to secure starting performance of a vehicle and durability of the auxiliary battery by periodically charging the auxiliary battery.
However, we have discovered that since the auxiliary battery and the vehicle loads are generally configured to be connected to an output terminal of the LDC in parallel, power consumed in the vehicle loads at the time of variably controlling the voltage of the LDC for charging the auxiliary battery is also affected, such that the fuel efficiency of the vehicle may be reduced.